Recent works highlight the B cells involvement in multiple sclerosis (MS) pathology but their role remains poorly understood. It was previously described that activated memory B cells called 4BL due to the increased expression of 4-1BBL, an activation marker, induce pro-inflammatory response by activating T CD8+ lymphocytes. Those 4BL cells are also described in systemic inflammation in 80 years old people explaining the poor efficiency of vaccination in that sub population. Those 4BL cells can also induce anti-tumoral T cell response.

The hypothesize is that 4BL may induce a pathogenic inflammatory response in MS.

the aim to compare the proportion of peripheral (blood) 4 BL cells but also 4-BL cells in cerebro spinal fluid (CSF) in MS compared to healthy controls and to other inflammatory neurological disease but also non inflammatory neurological disease.

For all groups of patients and controls it will collect blood and CSF only once (at diagnosis time for patients).

Blood collect from healthy controls will come from transfusion volunteers and we won't have CSF from them.

For patients from the MS group, the blood collect will be sequential at diagnosis, 3, 6, 12 and 24 months after during the follow up.

In the blood and CSF we will evaluate:

• percentage of 4 BL cells. 4 BL cells are found using cytometric parameters
• capacity of 4 BL cells to induce inflammatory response in vitro: percentage of induced activated TCD8 proliferation after cell culture using extracellular and intracellular cytometric parameters

Inclusion Criteria for MS group:

• MS defined by McDonald 2017 criteria with a disease duration of less than 1 year
• between 18 and 60 years old patients
• naïve of any immune therapy or steroid intake
• patients who signed consent to the study

Inclusion Criteria for controls with inflammatory of non inflammatory neurological disease:

• patients who signed consent to the study
• between 18 and 60 years old patients
• naïve of any steroid intake or immune therapy

Inclusion criteria for healthy controls:

• control who signed consent at transfusion center for their blood collect to be used for study
• between 18 and 60 years old patients
• naïve of any steroid intake or immune therapy

Exclusion Criteria:

• pregnancy or breast-feeding
• patients or controls unable to sign the consent or to consent

MS patients and controls: healthy controls and patients having non-MS neurological inflammatory disease and patients having other non inflammatory neurological disease.